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Title:
METHOD FOR INSTALLING A SUBSEA JUMPER AS WELL AS SUBSEA JUMPER
Document Type and Number:
WIPO Patent Application WO/2017/034406
Kind Code:
A1
Abstract:
The invention concerns a method for installing a subsea jumper (10) as well as a subsea jumper, comprising a first determination step in which the relative position of a first connection hub (18) to a second connection hub (19) on the seabed is determined, a fabrication step wherein a jumper is fabricated such that the relative position of the first jumper connection hub (12) with respect to the second jumper connection hub (11) corresponds with the relative position of the first connection hub with respect to the second connection hub as obtained in the first determination step. In a second determination step the mutual position and orientation of the connection hubs (18, 19) are determined, then the mutual position and/or orientation of the jumper connection hubs (12,11) are adjusted to correspond with the relative position and orientation of the connection hub whereafter one or more sections of the jumper are bended.

Inventors:
FRIJNS TOM LAURENT HUBERT (NL)
SALOMÉ PETER (NL)
Application Number:
PCT/NL2016/050591
Publication Date:
March 02, 2017
Filing Date:
August 24, 2016
Export Citation:
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Assignee:
HEEREMA MARINE CONTRACTORS NL (NL)
International Classes:
F16L1/26
Foreign References:
GB2276696A1994-10-05
FR2565319A11985-12-06
FR453149A1913-05-31
US8425154B12013-04-23
GB2276696A1994-10-05
FR2565319A11985-12-06
FR453149A1913-05-31
US8525154B22013-09-03
Attorney, Agent or Firm:
HART, W.W.H. (NL)
Download PDF:
Claims:
CLAIMS

Method of manufacturing and installing a subsea jumper (10), in which method a first component connection hub of a first subsea pipeline system component is subsea connected to a second component connection hub of a second subsea pipeline system component;

wherein the method comprises the steps of:

• determining the relative position of the first connection hub (18) with respect to the second connection hub (19) in a first determination step;

• manufacturing a subsea jumper (10) comprising a first jumper connection hub (12), a second jumper connection hub (1 1) and a pipeline part (13) of rigid steel having one end integrally connected to the first jumper connection hub and the other end integrally connected to the second jumper connection hub, wherein in this fabrication step the relative position of the first jumper connection hub with respect to the second jumper connection hub is arranged to correspond with the relative position of the first connection hub with respect to the second connection hub as obtained in the first determination step;

• determining the mutual position and orientation of the first connection hub with respect to the second connection hub in a second determination step prior to an adjustment step;

• adjusting the mutual position and/or orientation of the first jumper connection hub (12) with respect to the second jumper connection hub (1 1) to correspond with the mutual position and orientation of the first connection hub with respect to the second connection hub as obtained in the second determination step prior to lowering the pipeline jumper in the water; wherein in this adjustment step one or more sections of the pipe line part of the jumper are bent by subjecting said one or more sections to plastic deformation with a bending device (30) positioned above the water surface; and

• installing the subsea jumper by lowering the subsea jumper into the water,

mounting the first jumper connection hub to the first component connection hub and mounting the second jumper connection hub to the second component connection hub.

Method according to claim 1 , wherein the determination in the first determination step is done with an accuracy of centimeters, such as with an accuracy of 2-30 centimeters.

3. Method according to one of the preceding claims, wherein the first determination step is done with LBL acoustic positioning.

4. Method according to claim 3, wherein the LBL acoustic positioning is done by a

pipeline laying vessel during the installation of the first subsea pipeline system component and the second subsea pipeline system component at the seabed.

5. Method according to one of the preceding claims, wherein the determination in the second determination step is done with an accuracy of milimeters, such as with an accuracy of 1-10 milimeters.

6. Method according to one of the preceding claims, wherein the second determination step is done by subsea metrology. 7. Method according to claim 6, wherein the second determination step is carried out with an ROV (Remotely Operated Vessel/Vehicle)

8. Method according to one of the preceding claims, wherein the fabrication step

comprises welding, coating and hydro-testing of the subsea jumper.

9. Method according to one of the preceding claims, wherein between the first

determination step and the second determination step, the first subsea pipeline system component and/or the second subsea pipeline system component are subjected to testing procedures, like flooding and/or hydrotesting.

10. Method according to one of the preceding claims, further comprising the step of subsea installing the first subsea pipeline system component with the first component connection hub and/or the second subsea pipeline system component with the second component connection hub.

1 1. Method according to one of the preceding claims, wherein the adjustment step takes place offshore, like on a vessel.

12. Method according to one of the preceding claims, wherein, in the fabrication step, the pipeline part of the subsea jumper is arranged to have one or more thickened sections with a wall thickness:

• thicker than the wall thickness of other sections of the pipeline part; or

• thicker than the wall thickness of the pipeline of the first or second subsea

pipeline system component. 13. Method according to claim 12, wherein the bending of the adjustment step takes place in the one or more thickened sections.

14. Method according to claim 12 or 13, wherein the subsea jumper fabricated in the fabrication step has straight and curved sections, the thickened sections being arranged in the straight sections.

15. Method according to one of claims 12-14, wherein the thickened sections have a wall thickness of 2-15 mm, such as 2-7 mm, thicker (than the other sections of the pipeline part or wall thickness of the pipeline of the first or second subsea pipeline system component, respectively).

16. Method according to one of claims 12 to 15, wherein the wall thickness of the non- thickened sections of the pipeline part of the subsea jumper is in the range of 12-60 mm, such as in the range of 18-30 mm.

17. Method according to one of the preceding claims, wherein the wall thickness of the pipeline of the first and/or second subsea pipeline system component is in the range of 12-60 mm, such as in the range of 18-30 mm. 18. Method according to one of the preceding claims, wherein the bending in the

adjusting step is performed with a three or four point bending device (30).

19. Method according to one of the preceding claims, wherein the manufacturing step is carried out on shore.

20. Method according to one of the preceding claims, wherein the bending in the

adjustment step is carried out on shore or on an installation vessel.

21. Method according to one of the preceding claims, wherein the second determination step is carried out with a different vessel than the vessel which installed the first subsea pipeline system component and the second subsea pipeline system

component .

22. Method according to one of the preceding claims, wherein the manufacturing step of the subsea jumper is carried out prior to the second determination step and the adjusting step is carried out after the second determination step. 23. Subsea jumper (10), such as a subsea jumper for use in the method according to one of the claims 1-22, wherein the subsea jumper comprises a first jumper connection hub, a second jumper connection hub and a pipeline part of rigid steel, wherein the pipeline part of rigid steel has one end integrally connected to the first jumper connection hub and the other end integrally connected to the second jumper connection hub, wherein the pipeline part has one or more thickened sections having a wall thickness which is thicker than the wall thickness of at least one other non- thickened section of the pipeline part.

24. Subsea jumper (10) according to claim 23, comprising:

- a pipeline part (13) which extends horizontally ,

- a first inverted U-shape (54) at one end of the pipeline part, the first inverted U-shape having an inner vertical leg (55) and an outer vertical leg (56), wherein the first jumper connection hub (12) is provided at an end of the outer vertical leg of the first inverted U-shape

- a second inverted U-shape (58) at a second, opposite end of the pipeline part, the second inverted U-shape having an inner vertical leg (59) and an outer vertical leg (60), wherein the second jumper connection hub (1 1) is provided at an end of the outer vertical leg of the second inverted U-shape, wherein at least one first thickened section (41 ,42) is provided in the inner and/or outer vertical leg of the first inverted U-shape, and

wherein at least one second thickened section (44,45) is provided in the inner and/or outer vertical leg of the second inverted U-shape, and

wherein at least one third thickened section (43) is provided in the pipeline part (13). 25. Jumper according to claim 23 or 24, wherein the pipeline part of the jumper has straight and curved sections, the thickened sections being arranged in the straight sections.

26. Jumper according to one of claims 23-25, wherein the thickened sections have a wall thickness of 2-15 mm, such as 2-7 mm, thicker than said at least one other non- thickened sections of the pipeline part.

27. Jumper according to one of claims 23-26, wherein the at least one non-thickened section of the pipeline part has a wall thickness in the range of 12-60 mm, such as in the range of 18-30 mm. 28. Jumper according to one of claims 23-27, wherein the diameter of the pipeline part is in the range of 5 to 18 inch (12.7 - 45.7 cm).

29. Jumper according to one of claims 23-28, wherein the distance from the first jumper connection hub to the second jumper connection hub is at least 10 m, such as at least 20 m.

30. Combination comprising:

- an installation vessel comprising a bending device (30) for bending the

subsea jumper (10) of any of claims 23-29, and

- the subsea jumper (10) of any of claims 23-29.

Description:
Title: METHOD FOR INSTALLING A SUBSEA JUMPER AS WELL AS SUBSEA JUMPER Field of the invention

The present invention relates to the field of subsea hydrocarbon fields and pipeline installations therefore, more specifically the invention concerns a subsea jumper and a method of installing a subsea jumper.

In offshore pipeline installations for subsea hydrocarbon fields, it is often a requirement to connect different components or structures to each other to make a fluid connection between the components. This can be for instance be connecting a pipeline to a well, a pipeline to another pipeline or a pipeline to a riser structure. To do this, both components to be connected are equipped with connector hubs. For the connection a so called (subsea) jumper is used. A jumper (also known as a jumper spool) is a section of pipeline with connector hubs on either end. The connector hubs on the jumper are connected to the connector hubs on both pipeline components to establish a connection between the components.

Background of the invention

The location where the connector hubs of the components to be connected end up on the seabed is subject to tolerances related to fabrication and installation, and can differ based on the pressure and temperature inside and outside of the pipeline.

Various connector systems exist in the market, in both horizontal and vertical configurations. These connectors do have limited flexibility to deal with inaccurate positioning of the mating connector parts.

A jumper is designed to be flexible such that, when the pipeline system is in use, a predetermined change in position of the connection points can be accommodated.

Connection points can move due to changing temperature or pressure of the pipeline components, or due to dynamic effects caused by for instance varying fluid mixtures passing through the pipeline, or moving riser systems. Jumpers can be made of various materials. Broadly jumpers can be differentiated in three types: flexible pipe jumpers, composite material jumpers and rigid steel jumpers.

A relatively simple solution, from an installation point of view, is to make the jumper from a so called flexible pipe. A flexible pipe is made from a number of separate layers which each have their own function, for example containing the product, or dealing with axial or radial tension. This has advantages in that the jumper is more flexible than a pipe made from solid metal. A simpler jumper design can be the result. A disadvantage is that flexible pipes are not available to suit all circumstances. Especially in very deep water, in combination with high internal pressures, the use of flexible pipes is frequently not possible.

Jumpers made of a composite material can be considered as well. These offer excellent flexibility properties, but not all composite materials can meet the required temperature ranges. A jumper made of rigid steel has the advantage that it can be accurately designed to meet large water depths, high pressures, and large forces. A disadvantage is that the material is relatively stiff, which, in order to meet the flexibility requirements, can result in complex shapes which can become large and heavy, and therefore difficult to handle and install. This is especially the case when dynamic loading is expected to occur.

A typical jumper can have a substantial size. The distance between the connection hubs may be in the order or 50 -100 meter or so. The jumper has a corresponding length. The inaccuracies in the positions of the connector hubs which need to be overcome by the jumper may be in the order of several meter.

Another issue is that in order to make up the connections at both connection hubs of the jumper, an accurate measurement of the position of the connector hubs of the pipeline components is required, before the jumper can be constructed in its final configuration. As there is limited possibility to adjust the connector hubs during installation of rigid steel jumpers, the distance between and position of the connection hubs on the jumper must be an accurate match with the relative position of the connector hubs of the pipeline

components at the time of installation.

A typical prior art installation sequence involving a rigid steel jumper has the following stages:

installing the pipeline components with the connection hubs, i.e pipelines with end terminations, riser structures, etc, on the seabed; flooding and hydrotesting of the pipeline components which usually cause the pipeline ends to move and consequently change in position;

perform subsea metrology to determine the position of the connection hubs of the components to be connected accurately in the x,y and z plane;

- design the final shape of the jumper on the basis of the data obtained with the subsea metrology;

cutting prefabricated jumper pieces to the exact length required and assemble these jumper pieces together by making closure welds;

subject the jumper to hydrotesting;

- coating the weld(s);

load the jumper onto a barge;

transporting the jumper to the location where it is to be installed for obtaining the connection between the pipeline components to be connected;

installing the jumper.

All this is a very time consuming process, which can postpone the completion of the work by weeks.

GB2276696 discloses a method of installing a pipeline jumper. The jumper has a horizontal section and two inverted U-shaped sections at opposite ends of the horizontal section. The horizontal section has a bend 9 which is shown in fig. 2. GB2276696 discloses that inaccuracies in the positions of the connectors 40,42 may be overcome in two separate ways.

According to the first way, the connectors are provided with funnels 44,46 which guide the ends 22,24 of the jumper on their way down, and in the process the funnels deform the jumper by exerting a force on the ends 22,24 of the jumper. In particular the horizontal section of the jumper is deformed at the bend 9 and at the inverted U-shaped sections.

According to the second way, the tension in the cables via which the jumper is suspended and lowered is changed to deform the jumper. In particular, the tension in cable 50 is changed relative to the tension in cables 48, 52 via which the jumper. This also causes a deformation of the jumper at the bend 9.

The method of GB2276696 has a drawback in that the magnitude of deformation which can be created, and therefore the magnitude of the inaccuracies in the positions of the connectors 40,42 which can be compensated, is very limited. The size of the funnels and the forces which they can exert on the jumper is very limited. Moreover, the variations which can be created in the tensions of the cables is also very limited. Because of this the method of GB2276696 is not suitable to be used in most real life circumstances, in which the inaccuracies of the positions of the connectors are simply too great. GB2276696 has another disadvantage in that the bending operation with the tension in the cables may result in an undesired rotation of the connectors 22, 24. This rotation may make it more difficult to install the jumper. Moreover, the rotation of the connectors may exceed the allowed rotation. This further limits the extent of the deformation of the jumper and the deviations in the positions of the connector hubs which can be overcome.

GB2276696 has another more general disadvantage in that the bending operation which is preferred is a plastic deformation. However, with the method of GB2276696 plastic deformation is difficult. Probably, the deformation which is created with the method of GB2276696 is elastic to a large extent. This is not preferred.

GB2276696 has another disadvantage in that the bending with the use of the cables cannot be controlled very well. Not only is the operation carried out under water at great depth, but the tension in the cables is difficult to control. It is also difficult to assess whether the result of the bending operation is according to requirements.

GB2276696 has another disadvantage in that there is simply no way of checking the integrity of the jumper after the bending process. A crack or local weak spot may have been created by the bending operation, but this will probably go unnoticed, resulting in a real risk of leakage and spills in hydrocarbons.

GB2276696 has another disadvantage in that the number of degrees of freedom between the connector ends of the jumper which the bending method allows is limited. There are four degrees of freedom involved, i.e. two rotations of one connector end relative to the other connector about two independent axes X,Y, a change in horizontal distance between the connector ends and a change in vertical distance between the connector ends. GB2276696 allows deformation in two or at best three degrees of freedom. With the method of

GB2276696 it is very difficult to change the vertical distance between the connector ends and it is also difficult to rotate one end in a controllable fashion about an axis Y which extends parallel to the horizontal section of the jumper.

All in all, GB2276696 discloses a very primitive and cumbersome way of installing a jumper. FR2565319 discloses a pipeline device having deformation boxes , see in particular figure 7. This device is intended to be used on land, not for subsea use. The overall shape of the device and the method of installation make this device unsuitable to be used as a subsea jumper.

FR453149 discloses a pipeline device intended to be used on land, not for subsea use. The overall shape of the device and the method of installation make this device unsuitable to be used as a subsea jumper.

US8525154B1 discloses a method of repairing a subsea pipeline. The method is carried out completely under water. Apart from the fact that this document does not relate to installing, but to repairing, a disadvantage of this method is that every step in the procedure is carried out under water. This makes effective control difficult and also makes it difficult to verify the quality of the end product.

Object of the invention

It is an object of the present invention to provide a method of installing a jumper which allows large deviations in the positions of the connector hubs, and which can be carried relatively fast.

The method should result in a safe end situation, i.e. a jumper connection having a known, high quality with substantially no risks of cracks or weak spots as a result of the deformation process. The invention

The current invention relates to a rigid steel subsea jumper and method of installing a rigid steel subsea jumper, and has as its object to reduce the above mentioned time consuming process considerably. According to a first aspect of the invention this object is achieved by the method according to claim 1.

According to the invention the jumper is prefabricated in a rough sizing on the basis of data obtained in the first determination step. Subsequently, the sizing of the prefabricated jumper is adjusted to mate more accurately with the first and second component connection hubs of the first and second subsea pipeline system components to be connected. This allows the jumper to be fabricated in a much earlier stage as the first determination can be done well before the second determination. Further the adjustment can be done offshore on site relatively close to the location where the subsea connection is to be established. Both result in a considerable saving of time. The accuracy of the first determination might be lower than the accuracy of the second determination. The accuracy of the first determination might be in the order of centimeters, whilst the accuracy of the second determination might be in the order of milimeters.

The first determination might be done with LBL (long base line) acoustic positioning. LBL positioning systems use transponder arrays with transponder separations from 100m to several km. The transponders are fixed to the sea floor and the object of which the position is to be determined.

The second determination might be done by subsea metrology. Subsea metrology is the process of acquiring accurate and traceable dimensional measurements for the design of subsea structures, primarily for interconnecting pipelines. These pipeline interconnections are required to join subsea assets to complete the flow of hydrocarbons from the reservoir to processing and storage facilities. Subsea metrology measurements are conducted to determine accurately the relative horizontal and vertical distance between subsea assets, as well as their relative heading and attitude.

Systems for LBL acoustic positioning as well as subsea metrology are available in the market. Further, the angular position of the components can be measured using bulls eye systems.

Data gathered in the first determination step can be used to prefabricate the jumper to roughly the required size, including welding, hydrotesting and coating of the jumper. The jumper might even already be transported to the field to perform the adjusting step offshore, so to say on site, on the basis of data gathered in the second determination step (which is more accurate than the first determination step and takes account for changes in position of the first and second component connection hub of the first respectively second subsea pipeline system components, which changes might have occurred after the first

determination step, for example as a result of testing the first and/or second subsea pipeline system components. Final adjustment of the jumper is done after the results of the second determination step become available. The final adjustment is done by controlled plastic deformation of designated sections of the pipeline part of the jumper using a bending device. To this end, the designated sections can be pre-determined and if needed, be made from a pipe part with a larger wall thickness than the rest of the pipeline part of the jumper.

The bending device can be a three point bending machine, with supports that are actuated by hydraulic cylinders. This is known in the art from a straightener of a reeling system.

The bending device can be positioned on the pipeline installation vessel or on shore. This allows to adjust the properties of the jumper before installation, making the process more time efficient. It also allows for more degrees of freedom, because the jumper can be deformed in multiple steps and be repositioned relative to the bending device after each bending step.

The bending on board the installation vessel also allows to measure and check the deformations and to verify that the deformations have not resulted in cracks or weak spots in the jumper. The same advantages occur when the bending operation is carried out on shore, although this requires an extra transportation step.

The bending according to the present invention allows for a controlled adjustment of the horizontal distance between the

Several further embodiments of the method according to the invention are described in claims 2-21. According to a second aspect, the object of the invention is achieved by providing a subsea jumper according to claim 22. Further embodiments of this subsea jumper according to the invention are described in claims 23-27.

Concerning the present invention it is in general noted that the jumper according to the invention can be used to provide a connection hub for connecting amongst others: one pipeline with another pipeline, a pipeline with a well, a pipeline to a riser structure, a well to a riser structure as well as any other component of a subsea pipeline system to another component of a subsea pipeline system (these components to be connected not necessarily are or comprise a pipeline).

The present application uses the terms 'relative position' and 'mutual position' of two parts with respect to each other. These terms are not intended to have a very different meaning, other than that the 'mutual position with respect to each other' might be much more accurate than the 'relative position with respect to each other'. The main reason for using different terms is to differentiate between the first determination step and the second determination step. The term 'relative position' is used in relation to the first determination step. The term 'mutual position' is used in relation to the second determination step. Similar applies to the terms 'mutual orientation' and 'relative orientation'.

Short description of the drawings The present invention will be further elucidated with reference to the drawings showing schematically an example of the method and jumper according to the invention. In these drawings:

Figure 1 shows schematically the installation of a jumper according to the invention to connect two subsea pipeline system components; and

Figures 2-4 elucidate very schematically the pre-fabricated jumper before adjustment

(Figure 2), the adjustment of the jumper (Figure 3) and the adjusted jumper mounted to two subsea pipeline system components to provide a fluid connection between these

components. Detailed description of the drawings

Figure 1 shows a first subsea pipeline system component 16 arranged on the seabed 20 and a second subsea pipeline system component 17 arranged on the seabed 20. The first subsea pipeline system component is provided with first component connection hub 18 in order to enable the first subsea pipeline system component 16 to be connected to another subsea pipeline system component, in this example the second subsea pipeline system component 17. This second subsea pipeline system component 17 is similarly provided with a second component connection hub 19. The connection of the first subsea pipeline system component 16 with the second subsea pipeline system component 17 is established via a jumper 10. This jumper 10 is made of a first jumper connection hub 12, a second jumper connection hub 1 1 and a pipeline part 13 of rigid steel. The pipeline part 13 of rigid steel extends from the first jumper connection hub 12, which is integrally connected to one end of the pipeline part 13, to the second jumper connection hub 1 1 , which is integrally connected to the other end of the pipeline part 13.

As can be seen in Figure 1 , the pipeline part 13 is assembled from multiple pipe sections of rigid steel which are rigidly connected to each other by welding. These multiple pipe sections comprise - in this example - six 90° curved pipe sections 26 and several essentially straight pipe sections 27, 28 of different lengths, which together define a M-like shape.

As can be seen in figure 2, the subsea jumper 10 comprises the pipeline part 13 which extends horizontally. The subsea jumper further comprises a first inverted U-shape 54 which is positioned at one end of the pipeline part. The first inverted U-shape has an inner vertical leg 55 and an outer vertical leg 56. The first jumper connection hub (12) is provided at an end of the outer vertical leg of the first inverted U-shape. It will be clear to the skilled person that the vertical legs need not be exactly vertical but that in practice some deviations are allowable. In particular rafter the deformation step the vertical legs need not be exactly vertical.

The jumper comprises a second inverted U-shape 58 at a second, opposite end of the pipeline part. The second inverted U-shape has an inner vertical leg 59 and an outer vertical leg (60). The second jumper connection hub 11 is provided at an end of the outer vertical leg of the second inverted U-shape.

At least one first thickened section 41 ,42 is provided in the inner and the outer vertical leg of the first inverted U-shape. It may also be that a thickened portion is only provided in one of the legs. At least one second thickened section 44,45 is provided in the inner and the outer vertical leg of the second inverted U-shape. At least one third thickened section 43 is provided in the pipeline part 13.

Together, these thickened sections allow plastic deformation in four degrees of freedom:

1. A change in horizontal distance between the connection hubs 1 1 and 12.

2. A change in vertical distance between the connection hubs 11 and 12.

3. A relative rotation between the connection hubs 1 1 and 12 about a first horizontal axis parallel to the pipeline part 13.

4. A relative rotation between the connection hubs 11 and 12 about a second horizontal which extends at right angles to the first horizontal axis, i.e. which extends orthogonal to the plane of drawing of figure 1 and 2.

Returning to figure 1 , in order to install the jumper 10 with its first jumper connection hub 12 onto the first component connection hub 18 and its second jumper connection hub 1 1 onto the second component connection hub 19, the jumper 10 is suspended by cables 23, 24 from a frame 21 , which in turn is suspended by cables 22 from a manipulation device (not shown). The manipulation device might be arranged above water level or in the water, but the frame 21 and all parts below it are under water.

In order to facilitate easier installation, the jumper might be provided with guiding jackets 14 and 15 enabling precise landing of the hubs 1 1 and 12 onto the hubs 19, 18 respectively. When the hubs 1 1 and 12 are placed onto the hubs 19, 18, respectively, the hubs 11 and 19, on the one hand, and the hubs 12 and 18, on the other hand, are mounted to each other in manner known as such, for example by bolts and/or welds. This installation process might be supported and/or assisted and/or monitored by ROV's 25 (ROV=remotely operated vessel).

For successful installation of a jumper of rigid steel, the mutual position and orientation of the hubs 1 1 and 12 of the jumper with respect to each other have to match the mutual position and orientation of the hubs 18 and 19 of the subsea pipeline system components with respect to each other as close as possible.

According to the prior art this is achieved by first fully installing and testing the first and second subsea pipeline system components and subsequently accurately measuring their mutual position by subsea metrology. Subsequently, the data obtained are used on shore to manufacture a jumper with perfectly mating hubs. All this takes a very considerable amount of time. Firstly as the full installation and testing of the subsea pipeline system components on the sea bed takes a long time, secondly because also the manufacturing of the jumper uses a long time.

According to the invention, this is achieved as follows:

• first a relatively roughly sized jumper is p re-fabricated on the basis of relatively less accurate position data obtained in a first determination step, this prefabrication includes all welding and coating so that one integral jumper results (opposite to a jumper consisting of several parts not yet assembled together);

• this p re-fabrication of the roughly sized jumper 10 can already take place in a much earlier stage resulting in that it is conceivable that the roughly sized jumper is already available before the installation and testing of the first and second subsea pipeline system components 16 and 17 is completed; • as shown in figure 2, see especially on the right the hubs 11 and 19, the hubs 1 1 , 12 of this prefabricated roughly sized jumper 10 will in general not mate perfectly with the hubs 19 respectively 18 of the subsea pipeline system components;

• as shown in figure 3, the pre-fabricated jumper 10 is adjusted by subjecting sections of the pipeline part 13 of the jumper to a bending operation resulting in plastic deformation of the section subjected to the bending operation; in the example of figure 3 the bending device 30 is a three point bender having supporting points 31 and 32 and pressure applying point 33 (or the other way around point 33 as supporting point and points 31 and 32 as pressure applying point, or all points 31 , 32, 33 as pressure applying points); This step is carried out prior to lowering the jumper into the water, preferably on board the installation vessel, and alternatively on shore.

• depending on the adjustment needed, multiple sections of the pipeline part 13 may be subjected to such a controlled bending by controlled plastic deformation;

• this adjustment is done on the basis of accurate measurements of the mutual

position of the hubs 18 and 19, which are also done in the prior art;

• As shown in figure 4, after this adjustment, the adjusted pre-fabricated jumper 10 can be installed and mounted, in conventional manner, with its hubs 1 1 and 12 onto the hubs 19 and 18 of the subsea pipeline system components 16 and 17. As can further be seen in figures 2 and 3, the pipeline part 13 of rigid steel is provided with thickened sections, in this example five thickened sections 41-45, where the wall thickness of the pipe section is 2-9 mm thicker than the wall thickness of the pipe section in non- thickened sections like sections 46-49. In the example of figure 2-4, the thickened sections 42-45 have been deformed, whilst the thickened section 41 has not been deformed as the situation did not require so.